This invention relates to a collapsible frame structure and more particularly to a portable structure of substantially unitary construction.
Collapsible frame structures of different types are well known. They range from simple tents to temporary buildings. The latter structures are commonly found in circuses, fairs, carnivals, or other places where a large number of temporary shelters are needed. These structures offer a great advantage over more permanent shelters in such circumstances because of their low cost, easy assembly and disassembly, and portability.
One form of a collapsible structure is shown in U.S. Pat. No. 3,744,195 to Ferkich. The frame structure comprises a number of members which are removably interconnected by bolts or the like. Each member is separate from others until joined together by the bolts to form the frame.
A second frame structure of tent form is shown in U.S. Pat. No. 3,085,586 to McDonough. The frame comprises a number of separate tubular beams that are fitted together in brackets and held therein by pins or set screws. Once the frame is constructed, it is erected by a winch to raise the upper frame section above the ground.
U.S. Pat. No. 1,590,072 to Belanger shows a portable tent structure. It includes hinges on its upper and lower frame sections to partially collapse the frame.
The approach illustrated by this prior art suffers from several drawbacks. The individual members of the frame are separate and must be assembled and disassembled in a time-consuming process whenever the frame is erected and collapsed. The overall structure is not easily moved once assembled. Moreover, the disassembled parts must also be carefully tracked to be sure that none is lost in the process of building or taking apart the structure.
Another approach is shown in U.S. Pat. No. 3,351,078 to Kleiman. Kleiman shows a car top camper that is simple to erect or collapse. The frame is of a connected, unitary construction and is erected by means of a series of winches and pulleys. However, Kleiman cannot be used as a temporary shelter. The frame is too small and fragile to support a building of normal size. Moreover, the Kleiman shelter does not readily collapse to a small, portable size but is still of substantial width in its folded position.
Therefore, a need remains for a mobile collapsible frame structure of sufficient strength to form a building of normal size and designed to be quickly erected and collapsed.